I am not sure what they are. I was just reading the post entitled "Stink Bugs" about 12 to 14 posts down from yours. Dave has a link to a picture of stink bug eggs in one of the replies. Go take a look. Could this be what they are???

I think they are sap balls for some reason, but can't remember where or how I came up with that. Maybe someone else can jog my memory, or maybe I'm thinking of something found on a different plant.

Take a couple of leaves and place them in a jar...see if anything hatches.

Uhh oh. those are the dreaded hornworm eggs. You might start checking other leafs. sorry to be the bearer of bad news. Mary

GET THEM OFF NOW! Seriously, Mary is right- those look exactly like hornworm eggs.
Although- if you have to prune lots of tomato plants regularly, you might want to put it in a jar as a cool little experiment. I saved a couple hatchlings myself just to watch them go through their life cycle, and it is really cool to watch them grow SO FAST! They are both cocooning as we speak (actually got to watch one dig down into the soil I put in the jar) If you have kids this would probably be really cool for them (or if you are a kid at heart like me...)
But seriously, GET THEM OFF!

Thank you everyone! Tonight, I meticulously searched the tomato plants for more eggs. Yesterday, I removed the ones I'd found & I didn't find anymore tonight.

Yeah, I was going to say they sounded like Hornworm eggs, even before I saw them. If you get any Hornworms that hatch, you can generally track them down by the sound of them eating, if you go into your garden when it is quiet. It will sound like, "scratch...scratch...scratch." Just follow the sound to the source, pick up the Hornworm and drop them on the ground and step on them. You can also sometimes follow them by their paths of destruction. I don't generally get Hornworms, and don't usually take any precautions, but I got a bad infestation one year and I wiped it out by sitting in the garden and listening.

I remembered last night that it was grapevines that have the sap balls. :) it was itching at me because I knew it wasn't quite right. And now I know what hornworm eggs look like. Cheers!